Screen Flow Equalization System

ABSTRACT

An assembly of inflow control devices on a string along with isolation devices can be delivered into an existing or newly delivered screen assembly that requires inflow control for balanced flow from the formation. In newly delivered screen assemblies, any gravel packing that needs to be done can be accomplished without the presence of the inflow devices for faster circulation and improved gravel deposition. External annular barriers can also be delivered with an original screen assembly in a new well installation. The inflow devices and barriers can be of a variety of designs and the internal string can be removable if the barriers are retrievable to facilitate further drilling or completion below the screen assembly.

FIELD OF THE INVENTION

The field of the invention is control of flow through screen sectionseither newly run or retrofit in existing wells by using internal flowcontrol devices on an inner string separated by barriers within thescreen and optionally for new installations additional external annularbarriers.

BACKGROUND OF THE INVENTION

Formations with long production intervals frequently provide an ofimbalance of the incoming flow along the interval that leads to problemswith water coning or other water production challenges, and alsoproduction of other undesirable fluids. Prior solutions have includedbalancing the flow along a long production interval with a plurality ofinflow control devices, which may be designed, tuned, or manipulated tosegment and distribute the inflow across the production interval toimprove the inflow characteristics. Typically these devices have beenintegrated into an assembly including sand screen systems.

Inflow control devices in the past were incorporated within sand screensystems which included a blank non-perforated base pipe with a screenmounted to it and sealed at opposed ends to define an annular spacebetween the base pipe and the screen surrounding it with an inflowcontrol device provided in fluid communication with both the main boreof the production tubing and this annular space to control the fluidinflow profile of fluids produced through that screen section, into theannular space, and into the production tubing. The produced fluid wouldflow along the base pipe and inside the screen to an inflow controldevice (ICD) which in the case of the Equalizer® inflow control devicesold by Baker Oil Tools included a spiral flow path whose resistance toa given flow rate could be designed to be higher in one location alongthe production interval or lower in another. Thus, any number of ICDscould be provided along a long production interval with zonal isolationbetween the segments including an ICD to segment and isolate the flowcharacteristics as desired to balance the production of fluid andprevent undesired production complications such as water coning or thelike. The operation of an ICD in this manner is well understoodthroughout the oil & gas completions industry, and for a given screensection, the flow would travel through the ICD and enter another annularspace with a hole or holes in the base pipe and from there all flowsfrom a collection of isolated screen sections would enter the base pipeand be conducted to the surface through a tubing string. Some examplesof screen assembly flow control and balancing systems are illustrated inthe following patents:

-   U.S. Pat. No. 7,413,022 Expandable flow control device;-   U.S. Pat. No. 7,409,999 Downhole inflow control device with shut-off    feature;-   U.S. Pat. No. 7,290,606 Inflow control device with passive shut-off    feature;-   U.S. Pat. No. 6,192,983 Coiled tubing strings and installation    methods;-   U.S. Pat. No. 6,112,817 Flow control apparatus and methods;-   U.S. Pat. No. 6,082,454 Spooled coiled tubing strings for use in    wellbores; and-   U.S. Pat. No. 5,896,928 Flow restriction device for use in producing    wells.

There are limitations to the integrated designs of screens with inflowcontrol devices described above. One limitation is the ICDs limit theability to circulate gravel packing slurries when trying to do a gravelpack on an assembly of screen sections. Another limitation is that forexisting installations that have an assembly of screen sections, thereis no way to use the above described integrated screen with ICD toretrofit an existing screened well without running in a second screenassembly inside the existing assembly, assuming space permits. Doing sowould greatly reduce flow altogether and create a new problem whentrying to solve the problem of misdistribution. Still further, the closetolerances in the screen annulus between the screen and base pipe ofconventional systems limits applicability of ICD usage for highlyviscous or heavy oil production.

The present invention is directed at the limitations described above andfocuses on decoupling the integration of the ICD from the primary sandscreen assembly and separating the ICDs from that screen assembly sothat, for example, a retrofit of an existing screen assembly can be doneto provide flow balancing to a screen assembly already in the hole; orso that the annular space along which axial flow occurs can be spaced asdesired limited only by the isolation capabilities of a particular zonalisolation device between isolated sections. This is accomplished bylocating a plurality of ICDs on a separate inner string separated fromone another by zonal isolation devices. The ICDs and the isolationdevices can be of a variety of types. The isolation devices arepreferably but not necessarily interventionless and allowed to setthemselves downhole, and the zones of interest can be adjacent orseparated by blank pipe. In that manner, an existing screen assemblywithout ICDs can be retrofitted for balanced flow to eliminate theissues relating to flow imbalance described above.

In new installations, ordinary screens with optional external annulusbarriers can be run in first and if needed, gravel packed without limitsto circulation normally posed by the presence of screens integrated withICDs and the lack of perforated base pipe along the production intervalfor taking circulation returns. After gravel packing, if required, theinternal string is run in with the ICDs the same as if the installationwere a retrofit operation described above. The internal zonal isolationbarriers straddle the ICDs to define discrete zones within the screensections. The zonal isolation barriers outside the screen can be selfactuating packers such as swelling packers. Alternatively, either theouter string with the sand screen or the inner string with the ICDs (orboth) can have ball seats and spaced seals around a port thatcommunicated to the external seals to set them. The internal barrierscan be retrievable to allow the string with the ICDs to be pulled frominside the screens to facilitate drilling or workover further downholeor to permit replacement of ICDs as production profiles change duringthe life of a well. These and other advantages of the present inventionwill be more apparent to those skilled in the art from a review of thedescription of the preferred embodiment and the associated drawingsbelow while understanding that the full scope of the invention is to bedetermined from the claims appended below.

SUMMARY OF THE INVENTION

A tubing conveyed assembly of retrievable or non-retrievable inflowcontrol devices on a tubing string along with isolation devices can bedelivered into an existing or newly delivered screen assembly thatrequires inflow control for balanced flow from the formation. In newlydelivered screen assemblies, any gravel packing that needs to be donecan be accomplished without the presence of the inflow devices and withconventionally perforated base pipe for faster circulation and improvedgravel deposition. External annular barriers can also be delivered withan original screen assembly in a new well installation. The inflowdevices and barriers can be of a variety of designs and the internalstring can be removable if the barriers are retrievable to facilitatefurther drilling or completion below the screen assembly.

In one aspect, an embodiment of the invention can include a wellborecompletion system, comprising an outer string including a plurality ofperforated base pipe joints. A plurality of such joints may beperforated and open to flow of reservoir fluid from an annulus betweenthe screen joints and a production zone of a reservoir; an inner inflowcontrol string may be provided within the screen joints. The innerstring may include at least a plurality of zonal isolation devicesdisposed along a string of non-perforated base pipe to control the flowof fluid along the inner string within an annulus between the inner andouter strings; and at least one inflow control device may be providedbetween at least two of the zonal isolation devices to control theinflow flow of fluid into the inner inflow control string.

In another aspect, an embodiment of the invention can include a methodof gravel packing a well, comprising the steps of: providing an outerstring including a plurality of perforated base pipe joints, wherein aplurality of such joints are perforated and open to flow of reservoirfluid from an annulus between the screen joints and a production zone ofa reservoir; providing a gravel pack work string within the outerstring; pumping a gravel slurry through the work string to deposit thegravel slurry within an annulus between the outer string and a wall of awellbore; removing the work string from the outer string; providing aninner inflow control string within the outer string, the inner stringincluding: at least a plurality of zonal isolation devices disposedalong a string of non-perforated base pipe to control the flow of fluidalong the inner string within an annulus between the inner and outerstrings; and wherein at least one inflow control device between at leasttwo of the zonal isolation devices to control the inflow flow of fluidinto the inner inflow control string.

In yet another aspect of the invention, an inflow control system canprovide inflow control to an existing completion having existingpermanently deployed perforated base pipe. The system may comprise aninner inflow control string within the outer string, the inner string,and may include at least a plurality of zonal isolation devices disposedalong a string of non-perforated base pipe to control the flow of fluidalong the inner string within an annulus between the inner and outerstrings. At least one inflow control device may be provided between atleast two of the zonal isolation devices to control the inflow flow offluid into the inner inflow control string, and the inner inflow controlstring adapted to be deposited and deployed within the existingpermanently deployed perforated base pipe.

In a further aspect, the invention may be directed to a method ofremediating an existing well completion, which includes an existingperforated base pipe. In such an embodiment, an inner inflow controlstring may be provided within the outer string, wherein the inner stringincludes at least a plurality of zonal isolation devices disposed alonga string of non-perforated base pipe to control the flow of fluid alongthe inner string within an annulus between the inner and outer strings.In such an embodiment, at least one inflow control device could beprovided between at least two of the zonal isolation devices to controlthe inflow flow of fluid into the inner inflow control string.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a retrofit assembly for an existing screen assembly to provideflow balancing capability;

FIG. 2 is a new installation of a screen assembly with external annulusisolators and a series of inflow control devices delivered on aninternal string with barriers to separate the inflow devices within thestring assembly;

FIG. 3 is a section view of a portion of an outer screen assembly withthe portion of the inner string assembly between two isolators installedin it.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A pipe joint as used herein includes a section of interest along acontinuous string of coiled tubing or other tubular goods and is notintended to be limited to threaded oil country tubular goods (“OCTG”). Astand is intended to mean a given length of interest of a tubular, andis not limited to any particular size or length or configuration of suchtubulars. Perforated can include holes or other apertures, or any sizeand shape or configuration of slots or other openings designed to permitflow therethrough. An inflow control device some examples of which are atortuous path, an orifice or other opening or path designed to limit ormoderate flow at a desired rate of inflow in one zone of interest withrespect to another zone of interest.

Referring to FIG. 1 a wellbore 10 which can be open hole or cased holehas a series of screen sections 12, 14, 16 and 18 joined together tomake an assembly 20. Although no blank pipe sections are illustrated inassembly 20 it is within the scope of the invention to use such blankpipe. An annular space 22 is defined between the assembly 20 and thewellbore 10. Incoming flow from the formation 10 is represented byarrows 24. That same flow enters the annulus 22 and flows along thatannulus 22 as indicated by arrows 26. The annular space 22 may have beengravel packed (not shown). In the retrofit embodiment of the invention,the above described structures are in the wellbore and the screenassembly has no devices for balancing the incoming flow but productionof water or the need to isolate a zone or zones that are producingundesired fluids is needed. In this embodiment of the invention, aninner string 28 that comprises preferably a plurality of inflow controldevices (ICD) 30 that preferably differ in the offered resistance to apredetermined flow rate of a given fluid is run into position in thescreen assembly 20. Each ICD allows flow into the inner string 28 asindicated by arrows 32. Isolation devices 34 preferably straddle theICDs 30 internal to the assembly while it is possible that the topmostand lowermost ICDs may only have an isolation device on one side. It isalso possible that some pairs of adjacent isolators 34 will have noICDs. Zones of the assembly that need to be isolated will not have anICD on inner string 28, for example. If the assembly 20 has blank pipethen the string 28 may also contain no ICDs 30 in the inner string 28for proper spacing out of the ICDs 30 to be adjacent to a portion of theouter string assembly 20 that has screen sections.

Those skilled in the art will realize that the inner string 28 can haveany number of ICDs 30 where adjacent ICDs 30 are separated by anisolator 34. The isolators 34 can be any style and can be permanent orretrievable. They can be swelling packers, mechanically set,hydraulically set or inflatables to name some possibilities. The ICDs 30can be of a variety of types. They can be tortuous paths or orifices toname a few possibilities. They can be sensitive to density or otherparameters to detect water or other undesirable fluid production andshut off. They can be selectively opened or closed and put intopositions in between with tools run in from the surface or with locallyassociated valve and operators that can be operated by control line,wireline or by remote operation from the surface such as with acousticsignals or by a sonde delivered to the proximity of a given ICD 30 tomove it fully open or closed or positions in between mechanically or bycommunicating to a locally mounted processor to trigger motor operationto reconfigure the ICD 30. If the barriers 34 are retrievable, theentire assembly of the string 28 with the ICDs 30 and barriers 34 can bepulled as an assembly to facilitate access for further drilling or tocomplete a previously drilled portion of the well or laterals exitingfrom a main bore.

Those skilled in the art will now appreciate that an existing well borehaving a screen assembly 20 that is made up of a series of perforatedbase pipes covered by a screen material that have no means for flowbalancing in a given zone can be retrofitted with an interior flowcontrol string 28 that at minimum has one ICD 30 and one barrier 34 forsubdividing the existing assembly of the outer screen 20 so that flowcan be balanced and even adjusted automatically or by surfaceintervention to change the flow regime through the assembly 20.

FIG. 2 is directed to a new completion and is virtually identical toFIG. 1 in all respects from an equipment standpoint except for theexternal isolators 36 placed between adjacent screen stands such as 14′.The method of use differs from FIG. 1 in that the assembly 20′ is firstrun in with the external isolators 36 to the zone or zones in question.An optional gravel pack can take place outside the assembly 20′ usingknown techniques with a crossover tool such that some or all of theannulus 22′ can be filled. At this time the inner string 28′ is notinside the assembly 20′ so that the ICDs 30 do not restrict fluidcirculation for the gravel pack and are not exposed to gravel erosionfrom the circulating fluid that is used to deposit the gravel. As aresult a better gravel packing can be accomplished in less time thanusing a screen assembly with integrated ICDs known in the prior art.

After the gravel packing equipment is removed the inner string assembly28′ as previously described can be run in. The external isolators 36 canbe set in a variety of ways after the gravel pack if one is required.The isolators 36 can set by swelling after a time exposure to wellfluids or by introduction of well fluids from the surface that triggerthe isolators 36 to set. The setting can be mechanical, hydraulic,hydrostatic or with a straddle tool to selectively actuate each isolator36 in a desired order. For example a space between two isolators 36 canbe gravel packed and an adjacent isolator 36 can be set before anadjacent annular zone 22′ is gravel packed. With a straddle tool thepreferred isolator style is an inflatable.

Alternatively, the inner assembly 28′ can spaced seals with a port inbetween that can straddle a fill port for a given isolator 36 so thatthe isolators 36 can be set using the inner assembly 28′ such as forexample with a series of seats to accommodate different size balls forsequential setting of the isolators 36 with inner string 28′.

In the preferred embodiment, the isolators 36 create discrete zoneswithin the annular space 22′ while the isolators 34′ create preferablyaligned zones in annulus 38 between the inner assembly 28′ and the outerscreen assembly 20′. For example zones 40 and 42 are axially aligned.The isolators 36 and 34′ are also axially aligned but offsets betweensuch isolator pairs are contemplated.

While the assembly 20 or 20′ is referred to as a screen assembly it isintended to encompass perforated pipe as well as a base pipe that hasopenings with a mesh or other type of overlay of a filtering device.

FIG. 3 illustrates a known screen 100 mounted over a perforated basepipe 102 with end seals 104 and 106. This assembly is a part of what hasbeen referred to as screen assembly 20 or 20′. A portion of the innertubular 28 or 28′ has the inflow control device 30 between isolators orbarriers 34.

The above description is illustrative of the preferred embodiment andmany modifications may be made by those skilled in the art withoutdeparting from the invention whose scope is to be determined from theliteral and equivalent scope of the claims below:

1. A flow distribution assembly for a screen assembly located downhole,comprising: an inner tubular string assembly comprising at least oneinflow control device and at least one isolator, said isolatorselectively actuated into contact with the screen assembly when saidinner tubular string is inserted downhole into the screen assembly todefine at least two flow zones through which fluid flow is balanced. 2.The assembly of claim 1, wherein: said at least one isolator comprisesat least two isolators disposed on opposed ends of said inflow controldevice.
 3. The assembly of claim 2, wherein: said at least one flowcontrol device comprises a plurality of flow control devices with eachpair of flow control devices having an isolator between them.
 4. Theassembly of claim 3, wherein: said flow control devices have differingresistance to the same flow rate of a predetermined fluid.
 5. Theassembly of claim 2, wherein: said at least two isolators comprises aplurality of isolators with at least on pair of adjacent isolators nothaving an inflow control device between them.
 6. The assembly of claim4, wherein: said isolators are retrievable to allow removal of saidinner tubular string to facilitate access to the wellbore past saidscreen assembly.
 7. The assembly of claim 1, wherein: said isolatorcomprises a swelling packer.
 8. The assembly of claim 4, wherein: saidisolator comprises a swelling packer.
 9. An assembly for balancing flowfrom a formation, comprising: an outer screen assembly defining an outerannulus between itself and a wellbore; an inner tubular string assemblycomprising at least one inflow control device and at least one innerisolator, said inner isolator selectively actuated into contact with thescreen assembly when said inner tubular string is inserted downhole intothe screen assembly to define at least two flow zones through whichfluid flow is balanced, said inner tubular string assembly defining aninner annulus between itself and said outer screen assembly in whichsaid isolator is disposed.
 10. The assembly of claim 9, furthercomprising: at least one external isolator disposed in said outerannulus.
 11. The assembly of claim 10, wherein: said inner and outerisolators are axially aligned.
 12. The assembly of claim 10, wherein:said inner and outer isolators are not axially aligned.
 13. The assemblyof claim 10, wherein: said external isolator comprises a swellingpacker.
 14. The assembly of claim 9, wherein: said at least one isolatorcomprises at least two isolators disposed on opposed ends of said inflowcontrol device.
 15. The assembly of claim 14, wherein: aid at least oneflow control device comprises a plurality of flow control devices witheach pair of flow control devices having an isolator between them. 16.The assembly of claim 15, wherein: said flow control devices havediffering resistance to the same flow rate of a predetermined fluid. 17.The assembly of claim 14, wherein: said at least two isolators comprisesa plurality of isolators with at least on pair of adjacent isolators nothaving an inflow control device between them.
 18. The assembly of claim16, wherein: said isolators are retrievable to allow removal of saidinner tubular string to facilitate access to the wellbore past saidscreen assembly.
 19. The assembly of claim 9, wherein: said isolatorcomprises a swelling packer.
 20. The assembly of claim 16, wherein: saidisolator comprises a swelling packer.
 21. The assembly of claim 16,wherein: said at least one external isolator comprises a plurality ofspaced isolators and said at least one internal isolator comprises aplurality of internal isolators, said internal and external isolatorsclosest to each other are either axially aligned or misaligned with eachother.
 22. The assembly of claim 21, wherein: said outer annuluscontains gravel between at least one pair of said outer isolators.
 23. Acompletion method for downhole use, comprising: providing an outerscreen assembly in a wellbore to define an outer annulus; inserting aninner assembly of a tubular string and at least one inflow controldevice and at least one internal isolator into the outer assembly thatis already in the wellbore to define an inner annulus between saidassemblies; actuating the internal isolator into contact with the outerassembly; defining by said internal isolator actuation a plurality ofzones through the outer screen assembly for flow balancing therethrough.24. The method of claim 23, comprising: gravel packing the outer annulusbefore inserting said inner assembly.
 25. The method of claim 23,comprising: providing at least one external isolator in said outerannulus.
 26. The method of claim 24, comprising: setting said externalisolator with swelling.
 27. The method of claim 23, comprising: settingsaid internal isolator with swelling.
 28. The method of claim 24,comprising: providing at least one external isolator in said outerannulus; setting said external isolator after said gravel packing. 29.The method of claim 28, comprising: using a swelling packer for saidexternal isolator.
 30. The method of claim 23, comprising: providing, onsaid inner assembly, a plurality of spaced inflow control devicesseparated from each other with a plurality of internal isolators. 31.The method of claim 30, comprising: providing different resistance to agiven flow of a predetermined fluid among said inflow control devices.32. The method of claim 25, comprising: setting said external isolatorwith said inner assembly.
 33. The method of claim 23, comprising: makingsaid internal isolator retrievable; unsetting said internal isolator;pulling the inner assembly out of said outer screen assembly; conductingdownhole operations beyond said outer screen assembly.